FAULTBASE
Error CodesASKCars
© 2026 FAULTBASE
All rights reserved.
v2.0.0 • Production
ContactPrivacyImpressum
What are the signs that my 2022 Toyota Highlander's thermostat is failing? - Toyota Highlander
Home/Cars/Toyota/Highlander/Fourth Generation (2020-present)/What are the signs that my 2022 Toyota Highlander's thermostat is failing?

What are the signs that my 2022 Toyota Highlander's thermostat is failing?

Toyota Highlander Fourth Generation (2020-present)

Error Codes
2-3 hours
Time
medium
Difficulty
medium
Severity
Navigation
ProblemSymptomsDiagnosisSolution
ProblemSymptomsDiagnosisSolution
4 min read
683 words

Problem Statement

Learn about the symptoms, diagnostic steps, and repair instructions for a failing thermostat in your 2022 Toyota Highlander.

Affected Component
thermostat
Estimated Time
2-3 hours

Symptoms

  • •Engine Overheating
  • •Engine Running Cold
  • •Coolant Leaks
  • •Poor Fuel Economy
  • •Unusual Engine Noises

Diagnostic Steps

  1. 1
  2. 2
  3. 3
  4. 4
  5. 5

Solution

💡 Expert Tip

For complex repairs like this, consider taking photos at each step. This helps if you need to reverse a step or consult with a mechanic. Also, keep all removed parts organized - you may need to reference them during reassembly.

Verification

After completing the repair, verify that the issue has been resolved:

  • ✓Test the affected component to ensure it functions correctly
  • ✓Check for any error codes or warning lights
  • ✓Monitor the vehicle for a few days to ensure the issue does not recur

Prevention Tips

To prevent this issue from occurring again:

  • •Follow the manufacturer's recommended maintenance schedule
  • •Address warning signs early before they develop into major issues
  • •Use quality parts and fluids recommended for your vehicle
  • •Keep detailed records of all repairs and maintenance

Tools & Equipment Required

  • •OBD-II scanner
  • •Pressure tester for the cooling system
  • •Thermometer
  • •Pot for water test
  • •Socket set and wrenches
  • •Screwdrivers
  • •Coolant
  • •Thermostat gasket (if applicable)
  • •Replacement thermostat

Additional Information

Affected Component
thermostat
Estimated Time
2-3 hours
Difficulty
medium
Severity
medium
Tools Required
9 items

Related Faults

Loading...

Share this solution

Comments

Sign in to share your thoughts

Sign In

No comments yet

Be the first to share your thoughts

Back to Generation
Signs of a Failing Thermostat in a 2022 Toyota Highlander

A failing thermostat can lead to various engine performance issues and may cause overheating or underheating of the engine. Here are some common symptoms of a failing thermostat in your 2022 Toyota Highlander:

  1. Engine Overheating

    • Symptoms: The engine temperature gauge rises above the normal operating range, or the engine warning light activates.
    • Cause: A stuck closed thermostat can prevent coolant flow, causing the engine to overheat.

  2. Engine Running Cold

    • Symptoms: The engine temperature gauge remains low, and the cabin heater produces lukewarm or cold air.
    • Cause: A stuck open thermostat allows too much coolant to flow through the engine, preventing it from reaching optimal operating temperature.

  3. Coolant Leaks

    • Symptoms: Puddles of coolant (a green, orange, or yellow liquid) under the vehicle.
    • Cause: A failing thermostat can lead to pressure build-up in the cooling system, causing hoses or the thermostat housing to leak.

  4. Poor Fuel Economy

    • Symptoms: Noticeable decrease in miles per gallon (MPG).
    • Cause: An engine that runs too cold may lead to incomplete combustion, affecting fuel efficiency.

  5. Unusual Engine Noises

    • Symptoms: Gurgling or bubbling sounds from the engine bay.
    • Cause: Air pockets in the cooling system due to thermostat failure may create noise.
Tools Required
  • OBD-II scanner
  • Pressure tester for the cooling system
  • Thermometer
  • Pot for water test
  • Socket set and wrenches
  • Screwdrivers
  • Coolant
  • Thermostat gasket (if applicable)
  • Replacement thermostat
Repair Instructions

If you have confirmed that the thermostat is faulty, follow these steps to replace it:

  1. Preparation

    • Ensure the vehicle is parked on a level surface, and the engine is cool.
    • Disconnect the negative battery terminal to prevent any electrical issues.

  2. Drain Coolant

    • Place a drain pan under the radiator.
    • Open the radiator drain valve and drain the coolant into the pan.

  3. Remove Old Thermostat

    • Locate the thermostat housing (typically near the engine where the upper radiator hose connects).
    • Remove the bolts securing the thermostat housing using a socket set.
    • Disconnect the housing and remove the old thermostat.

  4. Install New Thermostat

    • Clean the mating surfaces of the thermostat housing and engine block to remove old gasket material.
    • Place the new thermostat in the housing, ensuring it is oriented correctly (usually, there is a small jiggle valve or bleed hole that should be at the top).
    • Install a new gasket if required and reattach the thermostat housing.

  5. Refill Coolant

    • Close the radiator drain valve.
    • Refill the cooling system with new coolant, following the manufacturer's specifications.

  6. Bleed the Cooling System

    • Start the engine and allow it to reach operating temperature with the radiator cap off to let any trapped air escape.
    • Monitor the temperature gauge and check for leaks.

  7. Final Checks

    • Reconnect the negative battery terminal.
    • Dispose of the old coolant properly.
    • Test drive the vehicle to ensure it operates within the normal temperature range.

By following these steps, you can effectively diagnose and replace a failing thermostat in your 2022 Toyota Highlander.